The apparatus and method of the invention has several advantageous uses. One such use is to install ducts, cables or pipes (herein collectively referred to as ducts) adjacent to existing plant such as electricity, telecom or other utilities. The installers of new ducts such as this are frequently faced with the problem of increasing the capacity of the system along a particular length of the said system.
Conventionally, new plant installations were installed along the existing ducts and along which existing plant ran in groups between access manholes. At the time of laying the existing ducts, additional spare capacity was normally provided but, as the requirement for new systems and equipment has greatly increased in recent years, it is increasingly found that the spare capacity has been used up and therefore installation of new ducts is required.